We risk watching them decline from coral bleaching, then dissolving through the oceans becoming more acid, and both happening before the sea level rises much.

Two significant milestones in understanding the influence of climate change on coral reefs were reached recently. First, the Commonwealth Government's own Great Barrier Reef Marine Park Authority (GBRMPA) issued an 'Outlook Report' examining the prospects for the Great Barrier Reef. Second, an international group of coral-reef experts convened by London's Royal Society published a report - endorsed by national and international peak bodies of coral-reef scientists - in the Marine Pollution Bulletin. Neither group could be considered fringe greenies alarmists. Both speak from deep experience and understanding of how coral reefs work. Both have a deep understanding of how reefs interact with the physical environment that humans are rapidly changing. What both have concluded is deeply worrying, but at the same time, press coverage of both reports was strangely muted.

GBRMPA rates the Great Barrier Reef's outlook as "poor", with many components of the Reef "already showing some effects from climate change". GBRMPA says adverse effects are evident at today's atmospheric CO2 level of 387 ppm, and predicts "serious consequences for the GBR" if CO2 levels increase above the range of 387 to 400 ppm.

The Royal Society group concluded that CO2 already in the atmosphere will "lead to an irreversible decline" in coral reefs unless levels are reduced to something like 320 ppm. Because the ill effects come from both increased temperatures and increased ocean acidification, the group advocates enhancing and creating CO2 sinks in addition to strong cuts to CO2 emissions. Until these efforts lower atmospheric CO2 levels, the group calls for a series of actions and policies to, in effect, keep coral reefs on life support.

So, what is new? We've heard before that the Barrier Reef is under threat. The difference is the much lower CO2 levels at which we now know that major, perhaps catastrophic, damage will occur. Only last year, the Garnaut Report said that coral bleaching would double at 450 ppm, and the 'reef as we know it' would disappear by 550 ppm. For months we have watched policy makers in Canberra struggle to agree on a formula to find solutions to the warnings in the Garnaut Report. The scary part is, those warnings, and the current policy debate, may not have gone far enough.

The question for Australians to ponder about the Barrier Reef – indeed all coral reefs - is this: do we take an evidence-based approach? Australia is the worst emitter of greenhouse gasses on a per capita basis of any industrialised nation. And a recent poll found that climate change has slipped well down the list of concerns for Australians. Ironically, we are amongst the countries with the most to lose. Do we really want one of the costs of our climate change policy to be the loss of the natural wonder of the Great Barrier Reef? Are we willing to let the Barrier Reef go? Does it have to be loss by neglect or half-hearted action?

No. There are many examples where Australia has taken decisive and successful action based on scientific evidence. In 1988 Australia was one of the first countries to sign the international Montreal Protocol, providing for legally binding reduction goals for the use of ozone depleting CFC’s. Faced with overwhelming evidence that almost every species of whale had been hunted to the verge of extinction, the Commonwealth government decided to end whaling in Australian waters in 1979 and has since become an advocate for whale protection internationally. These are clear demonstrations of the benefits of taking early evidence-based action.

We now know that slowing the rate at which CO2 is building up in the atmosphere is not enough to save the Barrier Reef. We now know that even maintaining atmospheric CO2 levels at their current levels may not be enough to save the Great Barrier Reef. If we want to save our reefs, we need to take the scientific advice, and push for action domestically and internationally which will lower CO2 concentrations in the atmosphere. Australia needs to act in Copenhagen as it has acted on the whaling debate, that is, act decisively to develop an Australian policy position which sets an example to the world, then argue hard for that position on the international stage. And we need to do it now.